1. Field of the Invention
The present invention is related to a system that causes artificial aging of electrical windings, wherein the system is mostly applied as an accelerated thermal aging test on stator bars or stator windings of electric machines.
2. Description of Prior Art
Stator bar or stator windings of big synchronous machines or electric machines that are in continuous service are exposed to aging factors such as heat that deteriorate the insulating material gradually, and unless there is regular monitoring and maintenance, complete machine failures can occur. Failures of these machines are extremely costly.
One monitoring system is the accelerated thermal aging of the stator bar wherein external heat is applied externally to the stator bar by means of an oven (see Electrical Insulation for Rotating Machines, Design, Evaluation, Testing and Repair, Stone, G. C. et al., page 59, IEEE Press Series on Power Engineering, Wiley-InterScience, 2004, ISBN 0-471-44506-1), or by means of a heating plate (see China Patent Publication No. 1402413A or 1162953C by HENGKUN, YUE XIE, Abstract).
Applying heat externally or causing heat by conduction to the stator bar during the described accelerated thermal aging test has the limitation of no simulating how heat is generated in the stator bar during the normal operation of the electric machine. Under normal operation conditions of an electrical machine, the stator bar heat is generated internally by induction because of the electrical current passing through the internal conductive component of the stator bar.
The present invention simulates how heat is generated in the stator bar when an electric machine is operating.